BVSS 2020 P1 Solution

2 1 Role Description Address bus • • Intermediate or final results produced by the computer; usually in the form of processed data. Memory • • Processes data and follows instructions; consists of an arithmetic logic unit and a control unit. Output • • Stores data, instructions and the results of processing for immediate use. Processor • • Stores large amounts of data that will not be lost when power supply is interrupted. Secondary storage • • Transports data between memory and processor; bi-directional. • Transports required memory location from processor to memory; uni-directional. 2 (a) Magnetic, optical, solid-state. (b) Magnetic Advantages: - Large storage capacity of up to terabytes (TB) of data. - Relatively cheaper than optical and solid-state external storage.

3 Disadvantage: - Vulnerable to drops and mechanical shocks. Optical Advantage: - Large storage capacity of up to gigabytes (GB) of data. Disadvantages: - Data can only be written once for some non-rewritable formats. - Lower maximum storage capacity than magnetic external storage. - Vulnerable to scratches and fingerprints. Solid-state Advantages: - Much faster than magnetic or optical external storage. - Not as vulnerable to drops, mechanical shocks, scratches or fingerprints. - Smaller in size and lighter in weight than magnetic or optical external storage. - Uses very little power and produces no noise. Disadvantage: - Much more expensive than magnetic or optical external storage. 3 Input: Date: date of day; must be a whole number between 1 and 30 inclusive (provided 30 times, once for each day). Rainfall: rainfall for day; must be a number greater than or equal to 0 (provided 30 times, once for each day). Output: The date with the lowest amount of rainfall. Process: Step 1: Assign 0 to a variable called var_date. Step 2: Assign 100 to a variable called var_amount. Step 3: Get the amount of rainfall. Step 4: Check if the amount of rainfall is lesser than the value of var_amount.

4 Step 5: If so, assign the amount of rainfall to var_amount, get the date and assign it to var_date. Repeat Step 3 to Step 5 for each day of the month. Step 6: Display the value of var_date. 4 decomposition incremental modular pattern recognition generalisation 5 (a) NAT (b) GPR (c) K T (note space between K and T) (d) True (e) hello WORLD 6 (a) Number Tries Won Guess OUTPUT 50 5 False 25 4 Guess higher 75 3 Guess lower

5 50 2 True 0 You win (b) To guess an assigned number within 5 tries. (c) Range check and presence check Range check ensures that input data is within the required range of values. Presence check ensures that all the required inputs are provided. 7 A compiler translates source code into machine code completely before running while an interpreter translates source code into machine code while the interpreted program is running. [1 mark for compiler, 1 mark for interpreter] 8 Line 11 WHILE exit_program = FALSE Line 16 cca_counter[my_cca - 1] += 1 Line 20 IF cca_counter[i] > highest_count Line 22 highest_count_index = i Line 25 OUTPUT cca_categories[highest_count_index] 9 (a) Phishing uses emails and fake websites that appear to be from reputable companies to steal personal information from users. - The email claims to be from a company or bank and asks for personal data or confidential information.

6 - The email uses a generic greeting such as “Dear Customer” or “Dear User”. - The email has inaccurate logos or grammatical and spelling errors that suggest it is not from a legitimate source. - The email seems to come from a fake sender or from an address or contact that does not match the supposed source of the email. - The email contains hyperlinks with destinations that do not match what the hyperlink text says or are otherwise unexpected. - The tone of the email or chat is excessively urgent or threatening. Alternatively, the email may promise an offer that seems too good to be true. (b) Pharming, spamming, spyware, Trojan horse, virus, worm. 10 (a) Method 1 2 | 155 2 | 77 r1 2 | 38 r1 2 | 19 r0 2 | 9 r1 2 | 4 r1 2 | 2 r0 2 | 1 r0 | 0 r1 Method 2 20 + 21 + 23 + 24 + 27 15510 = 100110112 (b) 00112 = 316 11002 = C16 001111002 = 3C16 (c) (1 x 163) + (14 x 161) + (1 x 160) = 4096 + 224 + 1

7 = 4321 10E116 = 432110 11 (a) The number systems are used to control the intensity of the RGB components. (b) Memory dumps, network addresses, ASCII and Unicode, URL encoding. 12 (a) (b) A B C Working Space X 0 0 0 0 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 1 1 1 0 0 1 1 1 0 13 (a) PMT

8 (b) COUNT, COUNTA (c) ROUND (d) =SUM(B8:B12), =B5-E3, =B4*E1 (e) B4, B5, B8, B9, B10, B11, B12, E2, E3 14 15 Modem 16 Wired networks are more reliable as data transmission is unaffected by interference. Wireless networks are less reliable due to potential interference from radio waves and microwaves or blockage from physical obstructions. 17

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